It is the Zippo Handwarmer, and brought to you by the makers of the famous Zippo lighters that have been around forever.Fill it with lighter fuel (can last between 12-24 hours depending on how much fuel you add), light the warmer up and place in the provided bag (you must use this bag, as the warmer becomes very hot).

Once you start it up to warm yourself, it is not that easy to stop from what I can gather (involves prying off the burning element without actually burning yourself), so you may want to be prepared to keep body parts warm for a long time.